Spray pump of the knapsack type



SPRAY'PUMP OF THE KNAPSACK TYPE Filed May 22, 193'? i?. f w. ROA/SM Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE Roland Lawrence William Robinson, South New Brighton, near Christchurch, New Zealand Application May 22, 1937, Serial No. 144,292 In New Zealand September 22, 1936 1 Claim.

This invention relates to spray pumps of the knap-sack type. In the case of a pump designed to create a high pressure in the end of the pumpbarrel through which the plunger-rod passes, there is always a tendency for a portion of the liquid to leak or escape from the pump-barrel past the packing-gland through which the plunger-rod works.

In a knap-sack pump a leakage of this kind results in the operators clothes becoming soaked with the liquid which is usually objectionable and sometimes of a dangerous or inflammable nature.

t is the object of the present invention however to provide a novel and simple construction whereby this difficulty may be overcome.

In carrying this object into eiect according to the present invention there is provided a double gland comprising a portion containing a packing for the plunger-rod as the latter passes to and from the pump-barrel, the outer end of such portion communicating by means of a closed chamber having a drain-passage leading to the upper of the liquid supply tank, with a second portion containing a packing designed to prevent the escape of liquid from the said chamber to the exterior.

In order that the nature of the invention and its construction may be clearly understood, it will now be more particularly described and eX- plained with reference to the accompanying drawing which shows in sectional elevation a pump and a portion of the supply tank equipped in accordance with the invention.

As here shown I is a pump-barrel mounted as customary upon the end of a liquid supply tank 2, such barrel I having an inlet 3 from the said tank and a delivery passage 4, while adapted to be reciproca-ted within the barrel is a bucketplunger mounted upon a plunger-rod 6 extending through the upper end of such barrel which is provided with a gland I having a packing 8 for the rod 6.

According to the present invention the outer end of the gland 'I is enclosed by a chamber 9 connected by means of a ldrain passage II] with the upper part of the tank 2 and provided with a second gland II having a packing I2 for the said rod to prevent leakage from the chamber to the 5 exterior.

In a preferred form of the construction, as here shownthe said gland 'I is contained in a threaded plug I3 screwed into the upper end of the bore of the barrel, while the second gland II, 19 together with the chamber 9 is contained in a cap-member I4 clamped upon the upper end of the pump-barrel by meansv of a union-nut I5.

In operation the arrangement is such that when a pressure of the liquid is created in the i5 upper end of the barrel I by means of the plunger 5, any liquid that may escape from such barrel past the gland-packing 8, will enter the chamber 9 where, being confined by the second glandpacking I2 such liquid Will be compelled to drain, 20 by means of the passage I0 back to the tank, thus precluding the possibility of any leakage occurring at the exterior of the pump.

I claim:

An apparatus of the type described comprising in combination, a liquid supply tank, a pump barrel connected to the liquid supply tank, a rod arranged within said barrel for longitudinal reciprocation therein, a plunger fixed to said rod so as to be moved thereby, a threaded plug and a packing gland surrounding the rod so as to close the end of the barrel, said barrel having an opening therein adjacent the plug to provide a discharge passage for the pumped liquid, a cap member surrounding the rod at the discharge end of said barrel and providing a chamber beyond sai-d plug, a threaded ring shaped nut for securing said cap member to the barrel, a second packing gland associated with said cap member and the rod to prevent leakage of the pumped liquid from the chamber to the exterior, and a pipe extending upwardly from said chamber to said supply tank.

ROLAND LAWRENCE WILLIAM ROBINSON. 

